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The Great Wall of China is the only man-made building that is so powerful that it can even be seen from outer space – the legend holds. He felt so strongly in the public consciousness that Neil Armstrong said the most common question he received after interviewing the moon on interviews and audience meetings was whether he had seen the big wall of the moon.

The slightly disappointing answer sounds, but it is worth recalling the most famous Earth photograph of the Moon, the Blue Glass Ball, which is the smallest, and remotely removable and identifiable thing of Madagascar.

(By the way, if we are here, perhaps the most famous photograph of the world originally reversed, the Southern Arctic is on top, the widely known version is rotated and cut.)

The legend of the Great Wall of China from the Moon dates back to the 1930s, at least the first written mention from 1932, Ripley’s Believe or Not! from the magazine, thirty years before the first-hand experience of what was seen about the moon and what was not. In fact, this statement should have been weak enough at that time, since the Moon is not nearly 350,000 kilometers closer to the Earth in the orbit, and it has been calculated by a good approximation by ancient Greek astronomers and mathematicians. This is a suspiciously long distance for a six meter wide (equivalent to a two-lane road), and just about the same high wall can be punctured.

But move on to the mutated version of the legend: is the wall visible from space? Of course, the definition of “space” should be defined first. The boundary between the atmosphere and the space is usually the Carman line, but of course it is quite ductile, with NASA at 80 kilometers and others at 100 km. Either way, the practical chance for mankind to look long is the closest to it, and already on the other side of the border at the International Space Station (ISS), approx. It is about 400 kilometers away, and the American space shuttle has also circulated at a similar height (between 300 and 500 kilometers).

However, the experience is that the wall is still not visible from here. Scientists have calculated that this perfect (ie ophthalmologist’s ability to read the smallest letters on the eye test board) would require 7.7 times sharper vision, but even an eagle’s or a hawk’s eyes would not be enough. Looking down on the ISS on Earth and seeing the great wall of China would be about half a kilometer wide to see a two-inch wide strip, which, with its color, blends well into its surroundings anyway. This is the second problem with the big wall beside its sheer size: its material does not fall sharply from its environment.

Jang Li-vej, the first Chinese astronaut in 2003 after his return, sadly announced that – national pride here or there – unfortunately, he had never seen the wall from above, though he had a great deal of eyesight and flew 14 times over China. This could be explained in the Chinese media: the weather conditions were bad and the spaceship was not trained for that. A year later, Leroy Chiao, a Chinese astronaut of Chinese origin, made a photo of irrefutable evidence of the ISS, which is a wall of a thin line somewhere in Beijing a few hundred kilometers north of somewhere in Inner Mongolia.


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